Developmental and Structural Section
Sarkar, Purbasha , Gladish, Daniel, K. .
Does Vascular Cavity Formation In Pea Primary Roots Involve Programmed Cell Death?
CELLS in the central vascular tissue of pea (Pisum sativum) primary roots undergo rapid lysigeny in response to hypoxic conditions created by flooding at 25°C. A long vascular cavity results that possibly provides a passageway for oxygen in a manner similar to cortical aerenchyma. Aerenchyma formation in cortex of maize and other plants involve programmed cell death (PCD). Vascular cavity formation may also involve PCD because presence of full-length cavities allows continued growth of the pea roots during flooding stress but growth stops in roots that fail to form cavities and also as the cell deaths are confined to specific tissues. A change in the localization pattern of cell wall pectins was observed in maize during flooding induced aerenchyma formation. The distribution pattern and abundance of esterified and de-esterified pectins in the walls of affected pea root cells were studied by in situ immunolabeling with anti-pectin antibodies (JIM5 and JIM7) followed by transmission electron microscopy. The mean number of de-esterified pectins per unit area in the cell walls did not change but esterified pectins were reduced by 40% (Student’s two-tailed t-test; P=0.058) in roots grown in flooded conditions at 25°C compared to unflooded controls. No significant change was observed between flooded and unflooded conditions when roots were grown at 10°C. Distribution pattern of de-esterified pectins also remained unchanged. Esterified pectins were more abundant in the middle lamella at 10°C, whereas they were more localized in primary cell wall at 25°C under both flooded and unflooded conditions. If these changes are shown to be under active regulation, it will be indicative of PCD. Current studies include staining of nucleic material with DAPI to detect any deformations in the nucleic material and using TUNEL assay to detect DNA fragmentation that are other identifying characters of PCD.
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1 - Miami University, Department of Botany, Oxford, Ohio, 45056, USA
2 - Miami University, Botany, 544, Mosler Hall, Hamilton, Ohio, 45011, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 303/Bell Memorial Union
Date: Monday, July 31st, 2006
Time: 8:00 AM